Kitchen sponges are full of bacteria and a DNA analysis of the so-called cleaning tools at a university in Germany found 362 different types of bacteria.
Researchers at Furtwangen University analysed 14 different kitchen sponges and discovered they had more bacteria than a toilet. According to experts, sponges, which are moist most of the time and designed for absorption, tend to attract bacteria like E coli, salmonella and Staphylococcus when used for cleaning dishes and counters or just from you touching it.
''Despite common misconception,'' the study reads, ''it was demonstrated that kitchen environments host more microbes than toilets.''
Most of the bacteria found were not harmful but there were pathogens that could cause infections in humans. Sponges could also spread bacteria to places where the microorganisms were not present.
''Kitchen sponges are likely to collect, incubate and spread bacteria from and back onto kitchen surfaces, from where they might eventually find their way into the human body, eg, via the human hands or contaminated food,'' the study said.
According to health professionals, sponges are best cleaned by microwaving for over a minute, soaking in a bleach solution for five minutes or using products with hydrogen peroxide, isopropyl alcohol, ammonia or vinegar - all of which have been said to kill 99.9 per cent of bacteria.
Kitchens, they add, are generally areas where new bacteria are regularly introduced, both due to human traffic and food preparation. Sponges, which are often warm, wet, and carry traces of old food, are ideal breeding grounds for those bacteria.
"Our work demonstrated that kitchen sponges harbor a higher bacterial diversity than previously thought," the authors wrote. The researchers also found five of the 10 most common bacterial groups had pathogenic potential, including Acinetobacter johnsonii, Chryseobacterium hominis and Moraxella osloensis. They further discovered that pathogenic groups that could lead to infection with E coli, S taph, or Strep, were present though, in low abundance.